Dose Responsive UV Indicator Using Delayed Color Change
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Solution Overview
Problem
Existing UV indicator devices provide little information on the level of UV exposure and fail to clearly indicate when the minimum erythemal dose (MED) has been reached, as they exhibit prompt or instantaneous color changes, making it difficult to determine relative UV doses over time.
Innovation Solution
A UV indicator system utilizing a combination of prompt and delayed UV-sensitive materials, where the delayed material changes color only after a specified UV dose is reached, optionally used with a prompt material for initial dose indication, and both are modified with UV-driven acid release agents and pH indicators to provide distinct color changes for different MED values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single gradual color change system is used in UV dosimeters, then the device structure is simple, but it is hard to identify useful stages in the development of sunburn such as MED=0.5 and 1
Solution Approach 1:
The patent divides the UV dosimeter into multiple segmented regions, each containing indicator layers that respond to different UV dose thresholds (MED=0.5, 1, 1.5, 2, 2.5, 3). This segmentation allows each region to display distinct color changes at specific dose levels, providing granular information about UV exposure stages while maintaining a relatively simple overall device structure.
2Reliability
If UV-driven acid release agents with pH indicators are used, then the color change mechanism is simple and reliable, but the color change occurs promptly or substantially instantly which does not allow determination of relative UV dose over time
Solution Approach 1:
The patent incorporates UV absorbers into specific indicator layers that prevent those layers from responding to UV radiation until a certain dose threshold is reached. This preliminary action of blocking UV radiation allows the system to delay the color change response until the appropriate cumulative dose is accumulated, enabling time-resolved dose determination while maintaining the reliability of the acid-release color change mechanism.
3Loss of information
If multiple indicator layers with different UV absorbers are used to show different MED values, then the information on UV dose levels is improved, but the device complexity increases
Solution Approach 1:
The patent structures multiple indicator layers in a nested arrangement where each layer contains a specific combination of pH indicators and UV absorbers. The layers are stacked sequentially, with each layer nested within the overall dosimeter structure. This nested organization allows multiple dose thresholds to be displayed in a compact format, providing comprehensive UV dose information without excessive structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system allows for a visual indication of UV dose over time, providing clear alerts for different UV exposure levels, including MED values, thereby helping users avoid overexposure and potential skin damage.
Implementation Method 1
The two key processes can be summarised as follows: HA→H++A− (1) D−+H+→DH (2) The result is that with UV irradiation time the deprotonated form of the dye, D, is converted into its conjugate acid form, DH and this is associated with a colour change
Implementation Method 2
given the nature of pH indicators, D− is very differently coloured to DH. For example, Thymol Blue (TB−) is yellow whereas TBH is red
Data Source
AI summary
A UV radiation (UVR) response indicator comprises a first UVB and/or UVA radiation sensitive material which has been modified so as to display an altered characteristic in a delayed manner in response to UVB and/or UVA radiation exposure. The UV indicator is capable of displaying exposure to increased UV radiation over a period of time. The present invention also relates to a method of displaying a relative amount of exposure to UVR by a UV indicator over a period of time. The invention is particularly useful in detecting the level of exposure to sunlight or sunbed radiation.